Swivel tip assembly and catheter using same

ABSTRACT

A swivel tip assembly ( 100 ) includes a housing ( 110 ) having a passageway ( 128 ) with proximal ( 112 ) and distal ( 114 ) openings. Spherical member ( 106 ) and bushing ( 108 ), which is captured by the housing ( 110 ), provide a swivel joint. A wire ( 102 ), which is coupled to the spherical member ( 106 ), is attached to the distal end of a catheter ( 50 ). The swivel joint allows the housing ( 110 ) to swivel or rotate freely thereby minimizing the opportunity of grabbing the guide wire ( 116 ) as the catheter ( 504 ) is being pushed or pulled along the guide wire ( 116 ).

FIELD OF THE INVENTION

[0001] This invention relates in general to the field of medicaldevices, more particularly, this invention relates to a swivel tipassembly and catheter using the swivel tip assembly.

BACKGROUND OF THE INVENTION

[0002] Catheters are well known in the medical field. The typicalprocedure for inserting a catheter into a patient is to first feed aguide wire into the patient until the distal end of the guide wire hasreached a target location inside the patient, for example, a portion ofa blood vessel that has a stenosis. Once the guide wire is in place, acatheter is feed through the proximal end of the guide wire. Thecatheter is then feed into the patient and tracked along the guide wireuntil the catheter has also reached the target location.

[0003] In a exemplary application, a percutaneous transluminal coronaryangioplasty (PTCA) catheter is feed through a guide wire that has beeninserted into a patient until the balloon carried by the PTCA catheterhas reached the target location (e.g., location of stenosis). Theballoon is then inflated in order to expand the vessel at the locationof the stenosis. After the balloon has been inflated at the targetlocation, it is deflated and the catheter is pulled back from the targetarea.

[0004] There are in general two main ways by which catheters track overa guide wire, the first is an “over-the-wire” design in which the guidewire lumen extends from the far distal tip of the catheter to the farproximal end. The second is a monorail system where the guide wire lumenis shorter than the catheter.

[0005] The advantage of the monorail (also call “rapid exchange”) designis that the shorter guide wire lumen allows a single operator to changecatheters conveniently. In one embodiment of the monorail system, theguide wire lumen is very short in length, for example, less than 2centimeter (cm) and the guide wire lumen is positioned at the far distaltip of the catheter. In these catheters where you have a short distalexchange guide wire lumen, by construction the guide wire exit portion(the proximal end guide wire port) may be in the tortuous portion of thevessel causing the catheter to potentially snag the guide wire. Theproblem that some times occurs when such a catheter is being pushed orpulled back along the guide wire is that the catheter may grab the guidewire and drag it along, especially when the catheter is being movedalong a tight bend in the vessel. This grabbing or snagging of the guidewire by the catheter affects the proper placement of the guide wire. Thecorrection of this problem is for the physician to work the guide wireback to its proper location. This sometimes may take a long period oftime to accomplish, especially if the guide wire has gone throughseveral tight bends. Given that time is of the essence when a patient isundergoing a surgical procedure such as PCTA, a need exists in the artfor a catheter, which can minimize the above-mentioned problem.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 shows a swivel tip housing attached to a swivel wire inaccordance with the preferred embodiment of the invention.

[0007]FIG. 2 shows the swivel wire and ball tip shown in FIG. 1.

[0008]FIG. 3 shows the swivel bushing shown in FIG. 1.

[0009]FIG. 4 shows a cross-sectional view of the swivel tip of FIG. 12.

[0010]FIG. 5 shows a PCTA catheter having a swivel tip in accordancewith the invention.

[0011] FIGS. 6-11 show some of the different manufacturing steps takenin order to manufacture the swivel tip assembly in accordance with thepreferred embodiment of the invention.

[0012]FIG. 12 highlights an alternate swivel housing assembly.

[0013]FIG. 13 shows a cross-sectional view of a portion of a radiationcatheter using the swivel tip assembly of the present invention.

[0014]FIG. 14 shows a partial cross-sectional view of an alternateembodiment of a catheter having a swivel housing and the swivel joint islocated within the catheter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] Referring now to the drawings and in particular to FIG. 1 thereis shown a swivel tip assembly 100 in accordance with the preferredembodiment. The swivel tip assembly 100 includes a housing 110 formedfrom high-density polyethylene (“HDPE”). Although HDPE is used in thepreferred embodiment, the swivel tip housing 110 could be formed ofother well-known materials used for medical applications as known in theart. The swivel tip housing 110 includes a guide wire passageway orlumen 128. The guide wire passageway 128 has proximal 112 and distal 114apertures or openings. The guide wire passageway 128 is used forreceiving a guide wire 116. Once the guide wire 116 is inserted intopassageway 128 a catheter (shown in FIG. 5 as one example) having theswivel tip assembly 100 is tracked along the guide wire 116 until itreaches the target location.

[0016] The use of the swivel tip assembly 100 helps reduce the snaggingor grabbing of the guide wire 116 by the catheter as previouslymentioned since the swivel tip housing 110 is able to rotate about wire102 and helps maintain a loose coupling to the guide wire 116. This isespecially helpful in reducing snagging of the guide wire while thecatheter is being maneuvered through one or more tight turns along avessel. The ability of the swivel tip housing 110 to freely swivel orrotate about wire 102 helps reduce any binding forces formed between thecatheter and the guide wire as the catheter tracks along the guide wire.

[0017] In the preferred embodiment, swivel tip housing 110 has anoverall length 118 of approximately 15 millimeters (0.59-inch). Guidewire passageway or lumen 128 has a diameter of approximately 0.432 mm(0.017-inch) and the distal portion of housing has an outside diameter124, at the noted location, of approximately 0.61 mm (0.024-inch). Theoutside diameter of housing 110 at its proximal end 126 is alsoapproximately 0.61 mm (0.024 inch). There is a slight bulge in swiveltip housing 110 at 122 where the outside diameter is approximately 0.86mm (0.034 inch). The distal end of the housing 120 is approximately 10mm (0.39 inch) in length. The proximal guide wire opening 112 of thehousing is angled (also referred to as a “skive”) to further reduce thepossibility of the guide wire 116 hanging up with the swivel housing 110as the swivel tip housing is navigated through tight turns.

[0018] A better view of a skived proximal opening 1202 is shown in FIG.12 which highlights an alternate swivel tip assembly 1200 having aslightly different housing shape. Housing 1204 includes a lumen 1208having distal 1206 and proximal 1202 openings or ports.

[0019] Attached to the swivel housing 110 as shown in FIG. 1 is anattachment member 102 that is inserted into housing 110 via aperture104. In the preferred embodiment attachment member 102 comprises a pieceof wire. Wire 102 is made from 304 stainless steel, although othermaterials known in the art can be substituted therefor. Wire 102attaches the housing 110 to a flexible elongate member such as acatheter (not shown). A section of wire 102 is preferably folded over asshown at its proximal end to allow for better attachment to a catheter(not shown). In the preferred embodiment, the swivel wire has anextension length 130 of approximately 5 mm (0.197 inch). The proximalend of the wire 102 (folded over portion) can be attached to a catheterusing an adhesive, heat bonding, or any one of a number of otherconventional attachment techniques. Preferably the attachment of thewire 102 to the catheter is done at the distal end of the catheter,although in different designs the attachment point may vary.

[0020] Instead of using a stainless steel wire as the attachment member102, other materials suitable for insertion into humans or animals andwhich would provide for a strong enough attachment so that the housing110 does not break away from the catheter may be used. Stainless steelwire is the preferred material in this embodiment, given the way theswivel tip assembly is formed by heat flowing the plastic in a jacket ormold as will be discussed further below to form housing 110.

[0021] At the distal end of the swivel wire 102 is a substantiallyspherical member such as a ball or sphere 106. A bushing 108 which isattached to the housing prevents the wire 102 from detaching given thatsphere 106 has a larger diameter than the diameter of the bushing'sopening. Heating the end of swivel wire 102 in a fixture forms the balltip 106. Any burrs that may form from this process are removed prior toinsertion of the swivel wire 102 into housing 110.

[0022] Alternatively, instead of making the ball 106 integral to swivelwire 102, ball tip 106 could be formed from a separate spherical memberthat is attached to swivel wire 102 by use of a number of knownattachment techniques (e.g., welding, soldering, crimping, etc.).Alternatively to using a spherical member 106 as shown, any other shapedmember (e.g., a cone shaped member, etc.) which would prevent thedetachment of the attachment wire 102 from the rest of the swivelassembly 100, and would allow for the free rotation of the housing 110about attachment member or wire 102 could be used.

[0023] In close proximity to ball tip 106 is a bushing 108, which isslid into swivel wire 102 from the opposite end of swivel wire 102 untilit reaches ball tip 106. Once the ball tip 106 and bushing 108 areinserted and pushed into to the end of aperture 104 which provides for aslip fit for ball tip 106 and bushing 108, the swivel tip housing 110 isheated using a hot torch fixture or other heat source. This heatingcauses the polyethylene housing to melt around the ball tip 106 andbushing 108 and fuses the bushing 108 and captures it within the housing110. The preferred method of manufacturing the swivel tip assembly 100will be discussed in detail further below.

[0024] Once housing 110 is cooled, the swivel wire 102 is rotated (usingthe portion external to housing 110) causing ball tip 106 and swivelwire 102 to break free of any melted polyethylene which may have adheredto them. and to freely rotate about bushing 108. Bushing 108 which isfirmly attached to housing 110 by the heating process prevents thedetachment of swivel wire 102 from housing 110. Ball 106 and bushing 108form a swivel or rotation point, which allows for housing 110 to swivelabout wire 102. Although a ball and bushing have been utilized in thepreferred embodiment, other designs which allow housing 110 to swivel orrotate about attachment joint designs may be used (e.g., a bearingencased in a housing member, etc.).

[0025] In FIG. 2, the swivel wire 102 having ball tip 106 is shown.Swivel wire 102 in the preferred embodiment has a diameter 204 ofapproximately 0.15 mm±0.05 mm (0.006-inch±0.0002 inch). The ball tip 106has a diameter 206 of approximately 0.28 mm±0.025 mm (0.011-inch±0.001inch). The overall length 202 of the swivel wire 102 and ball tip 106 is38.1 mm±12.7 mm (1.5 inch±0.5 inch). In FIG. 3, bushing 108 is shown.Bushing 108 has a length 302 of approximately 1.52 mm (0.060 inch), anoutside aperture diameter 304 of 0.33 mm±(0.013±0.00135 inch) and aninside aperture diameter of 0.178 mm±0.0127 mm (0.007±0.0005-inch). FIG.4 shows a length wise cross-sectional view of the swivel tip assembly1200 shown in FIG. 12. Swivel guide wire lumen housing 402 is differentin shape than housing 110 shown in FIG. 1. Arrows 404 highlight theability of housing 402 to rotate freely in either direction.

[0026] In FIG. 5, there is shown a flexible elongate member assemblysuch as a swivel tipped PCTA catheter assembly 500 in accordance withthe invention. Swivel tipped PCTA catheter 500 includes a PCTA catheter504 as is known in the art (e.g., a VINTAGE™ PCTA catheter manufacturedby Endosonics Corp.) and includes a swivel tip assembly 100 attached tothe distal end of the PCTA catheter 504.

[0027] The proximal end of the swivel wire 102 is attached to the distalend of the PCTA catheter 504 by bonding the wire using adhesive. Otherknown attachment techniques such as welding or crimping the swivel wire102 to the distal portion of catheter 504 can also be used depending onthe particular design. In the embodiment shown, swivel tip assembly 100is located distally of balloon 502.

[0028] The catheter with swivel tip assembly 500 in accordance with thepresent invention helps prevent the grabbing of the guide wire 116 asthe catheter assembly 500 is tracked over the guide wire 116. The swivelor rotation action provided by the swivel tip assembly 100 helps reducesnagging of the guide wire 116 especially while the catheter assembly500 is being tracked over a tight bend in a vessel (e.g., artery).

[0029] Referring now to FIG. 13, there is shown an radiation deliverycatheter 1300 that includes a swivel tip assembly in accordance with thepresent invention. Similar to the catheter shown in FIG. 5, the proximalend of wire 102 is adhesively or heat bonded at location 1302 to thedistal end of the catheter 1308. The guide wire lumen 128 allows thecatheter 1300 to receive a guide wire (not shown). Radiation catheter1300 includes a radiation section 1304, and an ultrasound section 1306which provides internal images of the vessel to help guide the radiationtreatment.

[0030] Although the above embodiments have shown the swivel joint, forexample in FIG. 1 comprising bushing 108 and sphere 106 located withinthe swivel housing, the swivel joint could be placed in the catheter inan alternate embodiment. This would cause the housing and attachmentmeans to rotate or swivel about the guide wire. Such an embodiment isshown in FIG. 14. The swivel housing 1402 is attached to catheter 1410via wire 1408 and a bushing 1406 and sphere 1404 are located within thecatheter 1410. In still another embodiment, the swivel joint could belocated between the swivel housing and distal end of the catheter andexternal to both.

[0031] An overview of the preferred method of manufacture of the swiveltip assembly will now be discussed in order to further help theunderstand of the present invention. The manufacturing process starts bycutting to length, two pieces 604 and 606 of HDPE 0.009″×0.024″ tubingto a length of approximately 5 cm each. The swivel bushing 108 is thenslid over a 0.178 mm (0.007″ mandrel) 602 then the two HDPE tubes 604and 606 are inserted into the mandrel as shown in FIG. 6 on either sideof the bushing 108. Next a Teflon™ forming jacket 702 is placed over theHDPE with the bushing 108 placed near the inner taper of the formingjacket 702 as shown in FIG. 7. The HDPE is then flowed inside of theforming jacket 702 using a heat torch operating at about 450° F.,allowing for the HDPE to flow completely around the bushing 108. Afterthe HDPE has cooled, the HDPE is trimmed flush to the larger side offorming jacket 702 using a blade.

[0032] The swivel bushing side (distal) of the jacket is again heated toreflow the plastic, while the HDPE is still under the torch and flowing,a spearcut mandrel 802, as shown in FIG. 8, is inserted into the HDPEfrom the larger diameter side, spear side first. The spear is insertedwith the spear face surface facing the bushing 108. Once the HDPE hascooled, the Teflon™ forming jacket 702 is removed. A ball tipped wire902 comprising ball 106 and wire 102 is inserted into the distal sideuntil the ball touches the bushing 108 as shown in FIG. 9. A piece ofinner lumen 0.432 mm×0.533 mm (0.017″×0.021″) 1002 is cut to a length ofapproximately 8 cm. A 0.432 mm (0.017″) mandrel 1004 is then insertedinto the inner lumen 1002. A forming jacket is then slid over the centerof the lumen as shown in FIG. 10. The jacket is then heated while bothsides of the inner lumen are pushed inward until it fills the proximalend of the jacket and about 3 mm of the distal end. The jacket is thenremoved and the HDPE is removed off of the mandrel.

[0033] Next as shown in FIG. 11, the HDPE tube is slid over the spearcutmandrel until the flared end butts against the swivel bushing assembly.A forming jacket is slid over the distal HDPE and over the proximalswivel assembly until it stops. A heat torch is then used to heat thecone of the jacket only until the distal plastic fuses with the proximalplastic. The forming jacket is then removed and the proximal end of theswivel tip is trimmed where the ball tipped wire straightens out in theplastic. The spearcut mandrel is removed and the distal end of theswivel tip is trimmed so that its length is approximately 15 mm. Theball tipped wire protruding from the proximal side is then folded overso that the length of the protruding wire is approximately 5 mm.Finally, a skive is added to the housing as shown in FIG. 1.

[0034] While the invention has been described in conjunction withspecific embodiments, it is evident that many alternatives,modifications, permutations and variations will become apparent to thoseskilled in the art in light of the foregoing description. For example,although the swivel tip assembly 100 has been shown using a sphere andbushing as the swivel point or joint for the swivel tip housing 110other alternative swivel joints known in the art can be used. Forexample, a snap-in ball joint design could be used instead of using abushing 108. Also, the swivel tip concept of the present invention canbe utilized not only with a PCTA or radiation catheters as describedabove, it can be used with other types of flexible elongated memberswhich can be inserted in patients or animals and that are tracked alonga guide wire:

What is claimed is:
 1. A catheter assembly which can track along a guidewire, the catheter assembly comprising: a catheter; a housing having apassageway for receiving the guide wire; a swivel joint located withinthe housing; and the housing is attached to the catheter by a wirehaving one end attached to the swivel joint and the other end attachedto the catheter.
 2. A catheter assembly as defined in claim 1, whereinthe housing is located distally of the catheter.
 3. A catheter assemblyas defined in claim 1, wherein the swivel joint allows the housing torotate freely about the wire.
 4. A catheter assembly as defined in claim3, wherein the catheter has proximal and distal ends and the wire isattached to the catheter at the catheter's distal end.
 5. A catheterassembly as defined in claim 3, wherein the swivel joint includes abushing.
 6. A catheter assembly as defined in claim 5, wherein thebushing is attached to the housing by melting the housing about thebushing.
 7. A swivel assembly for use with a flexible elongate memberwhich is tracked along a guide wire, the swivel assembly comprising: ahousing member including a passageway having proximal and distalopenings for receiving the guide wire; a swivel joint located inside thehousing member; and an attachment member attached to the swivel jointwhich allows the housing member to rotate about the attachment member.8. A swivel assembly as defined in claim 7, wherein the attachmentmember comprises a wire.
 9. A swivel assembly as defined in claim 8,wherein the wire and the housing's passageway are substantially parallelto each other.
 10. A swivel assembly as defined in claim 7, wherein thehousing is made from plastic.
 11. A swivel assembly as defined in claim10, wherein the swivel joint includes a bushing, which is fixed to thehousing.
 12. A swivel assembly as defined in claim 7, wherein theattachment member comprises a wire having a substantially sphericalmember at one end which is captured by the bushing.
 13. A catheterassembly which can track along a guide wire, comprising: a catheter; anda housing having a passageway for receiving the guide wire, and thehousing is attached to the catheter by a wire which is attached to aswivel joint located within the catheter that allows the housing torotate about the wire.
 14. A catheter assembly as defined in claim 13,wherein the housing is located distally of the catheter.
 15. A catheterassembly as defined in claim 13, wherein the passageway has distal andproximal openings and the proximal opening is skived to help reduce thepossibility of the guide hanging up with the housing.